The present disclosure relates generally to rotary machines, and, more specifically, to methods and apparatus for use in providing sealing between components within a turbine.
At least some known rotary machines, such as gas turbines, include a plurality of seal assemblies in a fluid flow path to facilitate increasing the operating efficiency of the gas turbine. For example, some known seal assemblies are coupled between a stationary component and a rotary component to provide sealing between a high-pressure area and a low-pressure area. In addition, at least some known gas turbines include at least one stator vane assembly and at least one rotor blade assembly that collectively form a stage within the gas turbine. In at least some known gas turbines, seals are provided between static components in adjacent stages, or between components within a stage.
In a turbine, e.g., a gas turbine, the compressor section includes a stationary inner barrel formed of two semi-cylindrical halves secured one to the other generally along a horizontal midline forming an annulus. The aft end of the inner barrel is secured to a compressor discharge casing which provides support for the nozzle support ring supporting the first-stage nozzles. The inner barrel, in part, segregates a high-pressure region external to the barrel from a lower pressure region within the barrel and about the rotor. One or more guide vanes are mounted stationary to an outer casing of the compressor in the last stages of the compressor section. The one or more guide vanes and the inner barrel are engaged so as to define a radial gap therebetween. A seal engages with the inner barrel during operation so as to preclude leakage flow therethrough. However, thermal expansion of one or more of the inner barrel, the guide vanes and the outer casing during operation of the turbine can leave a gap of sufficient dimension between the one or more guide vanes and the inner barrel to allow for leakage flow therethrough. As a consequence, leakage paths can and do appear between the one or more guide vanes and the inner barrel. A need has therefore arisen to minimize or eliminate any such leakage paths in a manner which is tolerant to thermal transient movement during turbine operation.